Facebook, Twitter, and other social media sites may not be happy if a new service that launched in beta Wednesday takes off.

The service, scrambls, may be misspelled and lack a proper capital letter, but it aims to put the control of social media posts back in the hands of users. Using scrambls, which is an add-on to major browsers, users can encrypt submissions to Facebook, Twitter, and other social networks, giving them fine-grained control over the scrambled text.

The service suggests interesting possibilities: Consumers could make their posts unreadable to anyone but themselves after three or six months, restrict access to certain posts to only family members, or block the social media site from using the posts for marketing purposes. Companies could create internal feeds unreadable by competitors and have an undo button to redact posts that leak sensitive information.

"The idea behind scrambls is that users need an opportunity to be in control of the content that they've posted," says Steven Sprague, CEO of Wave Systems, a maker of hardware-based digital security systems and the company that incubated scrambls as a startup. "If we believe that social media sites are not a toy, but are really a utility, then there needs to be a mechanism for more secure, more controlled, communication."

The service will be free to consumers, while companies will have to pay to use it.

Policies like "right to be forgotten" -- still on the drawing board in the European Union -- leave online users with an all-or-nothing choice: Give the social network access to your data or delete it, says Sprague.

"It's an incredible false choice. In reality, what we are doing, is contributing to a scrapbook, but we have this incredible uncertainty today" as to how the content will be used in the future, he says.

To highlight the point, Sprague trots out the example of his 14-year-old daughter, who uses Facebook and other social media sites.

"She's going to wake up one morning and realize that she is in college or going to get her first job, and all that stuff she typed in when she was 14 might not be the most appropriate thing to put on her resume. Then the only choice is to delete?" he says.

Sprague addressed a number of concerns regarding the service. For example, users will be able to back up the keys to their posts at any time, whether to recover their data if something happens to scrambl or to switch to a different service. The feature is not yet implemented, but Sprague pledged it would come.

The service uses, in essence, a one-time pad to scramble the message, and scrambls manages the keys, which are not reused. The encryption is not meant to protect an individual message from a brute-force cracking attempt, but to protect the body of a person's posts from prying eyes. It protects short messages extremely well and doesn't add to their length by much, an important feature for text-message-based services such as Twitter.

"A good way to think of the service in its beta form today is this is not about supersecrecy of an individual post," Sprague says. "This is about privacy and control first."

Social media companies will likely see the service as a threat. Users' posts are the currency of such sites, and not having the ability to control access to the content will likely not please social networks. But the capability also opens additional use cases for social media users, Sprague argues. Musicians, for example, could have VIP Twitter feeds; fans who buy an album or attend a concert could get a special key to access the feed for a month or a year.